All boats have many “through-hull fittings” which allow water to enter or exit a boat for various functions such as engine cooling, gray water drains, etc. The through-hull fittings typically have shutoff valves connected to a nipple and a hose. One reason for boats docked in harbor sinking is failure of one of these components. While at sea these components can also fail. In addition, the through-hull fitting has a lip on the outside of the hull and could break away upon an even slight direct impact or scraping, allowing the inward flow of water into the boat.
The current commercially available remedy for this are wood plugs that must be hammered in, using a mallet to lock the wood plug in place. Hammering wood plugs into the hull generally makes the hole larger. In inserting into a nipple, valve or fitting, the wood plug must also be hammered in place that can lead to a cracked nipple before the wood plug grabs enough of the fitting to stop the inward follow of water. The force needed to lock the wood plug in place could also split the nipple. The exact size of the wood taper plug is also needed for each through-hull fitting, or nipple.